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Philco 90 question
#1

I have a 90 chassis, the one with a single '47 output tube. I've been recapping this thing, and it's coming along pretty well, but there's one odd thing that I've noticed.

I keep having trouble with the '24 IF amp. Every once in a while it dies until I tap on it (the original one had an intermittent short in it, if it died and I tapped on it, it would come back, but I could see it arcing inside). What is interesting is, when the tube dies, or when I remove it completely, I can still hear the tuned in station in the speaker, although the volume control has no effect. I've tracked the signal paths and I find that all the bypass caps in the signal paths have already been replaced.

Both of the shields are missing. I have fashioned a shield around the IF amp, which seems to be very touchy, and breaks into oscillation at the drop of a hat, and this cleared up the oscillations.

Is it possible that I am going to have to locate the original shields in order to keep this 'ghost' signal out? I would not worry too much about it, but I'm thinking it may be out of phase and therefor cancelling some of the signal.

TIA


Messages In This Thread
Philco 90 question - by BrendaAnnD - 03-22-2013, 09:24 AM
RE: Philco 90 question - by morzh - 03-22-2013, 10:02 AM
RE: Philco 90 question - by BrendaAnnD - 03-22-2013, 06:21 PM
RE: Philco 90 question - by Ron Ramirez - 03-22-2013, 06:43 PM
RE: Philco 90 question - by BrendaAnnD - 03-22-2013, 09:50 PM



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